NBD has a very broad emission and will definitely bleed through filters
typically used for PE. I would suggest using a headgroup labeled FITC-PE
(avail from Mol Probes or Avanti) at about 0.1 mol % in the vesicle. Then
you would have the standard dye pair used for immunofluorescence as well as
the ability to determine number of vesicles bound per cell. You will need
to look out for self quenching of both these probes as well as energy
transfer between them if you want to be quantitative.
Good luck.
John P. Nolan, National Flow Cytometry Resource
Life Sciences Division, LS-5, M-888
Los Alamos National Laboratory, Los Alamos, NM 87545
Ph: 505-667-1623, FAX: 505-665-3024